WHAT’S UP DOC? AVM

By Dr. Jeff Hersh/Daily News Correspondent

Tuesday

Sep 4, 2018 at 3:20 PMSep 4, 2018 at 3:21 PM

Q: My neighbor was just diagnosed with an arterio-venous malformation. What is this?

A: An arterio-venous malformation (AVM) is a congenital condition (you are born with it) where some of the arteries (that carry oxygenated blood) and veins (that carry blood back towards the heart) do not form correctly; instead the arteries connect directly to the veins with no capillaries between them. An AVM can occur essentially anywhere in the body, but they are most common in the brain and spine.

It is not understood why somewhere between 1 and 10 per thousand people are born with an AVM; this is not an inherited condition, except in the rare cases where it is associated with a congenital syndrome such as Osler-Weber-Rundu or Sturge-Weber syndromes. In addition, somewhere between 5 and 25 percent of patients with a brain AVM also have at least one aneurysm (a sac-like protrusion from a blood vessel), and up to 10 percent have more than one AVM.

A brain AVM is usually discovered between the ages of 10 and 40 if/when the patient develops symptoms. The specific symptoms depend on the exact location, size and other characteristics (such as which blood vessels are involved) of the AVM.

Symptoms from a brain AVM are caused by the physical mass of it pushing on structures of the brain, bleeding from the malformed blood vessels or decreased blood supply to part of the brain (if too much blood flows through the AVM there may be insufficient blood to adequately nourish some brain cells). Increased overall blood flow during pregnancy (including through the AVM), makes it more likely for an AVM to become symptomatic.

Brain AVM symptoms may include seizures (which is the initial symptom in 10 to 30 percent of patients), headaches (which may be mild to severe, and which can be ‘migraine-like’), stroke symptoms (from insufficient blood supply to part of the brain), or symptoms from the AVM bleeding (which can range from headaches to stroke symptoms to coma or even to death).

Bleeding from a brain AVM is the most feared complication; it is the identifying event in about half of people with this condition, occurring in around 4 per 100 of these patients per year. When bleeding occurs, it leads to death up to a quarter of the time, and to permanent disability up to a quarter of the time.

The diagnosis of a brain AVM is confirmed with an imaging test such as an MRI, a CT or an angiogram (where a tube is inserted into one of the blood vessels and then threaded up towards the brain so a dye can be injected and seen on a special kind of x-ray). The MRI or CT can also be done with dye injected, making these an MR angiogram or a CT angiogram, respectively.

The details of someone’s brain AVM need to be considered to determine whether treatment is required; some patients with an un-ruptured AVM may be best served by a ‘watch and wait’ approach as treatment may be riskier than doing nothing.

When treatment is required it focuses on stopping the blood flowing directly from the arteries to the veins in the AVM, as well as at stabilizing the AVM to minimize its risk of rupturing.

Surgery to remove an AVM is a definitive treatment option; however, if the AVM is deep inside the brain, the complication risk is increased. Therefore, less invasive approaches have been developed.

Two less invasive approaches to treat brain AVMs are embolization and radiation treatment. Embolization of an AVM involves placing a thin tube into the patient’s blood vessels and advancing it to the AVM; from there either a special glue or possibly small coils are placed into the AVM to block the blood from flowing through it. Radiation therapy uses a focused beam (or beams) of x-rays or protons to concentrate high levels of energy on the AVM; over the course of treatment it shrivels up and closes. These minimally invasive therapies minimize the risk of rupture and/or improve symptoms caused by the AVM, but may not completely ‘cure’ it.

For some patients different treatments may be combined; for example, an AVM may be embolized and then subsequently treated with radiation therapy, or an AVM may be treated with embolization or radiotherapy to ‘stabilize it’ to minimize risks when it is surgically removed.

Research by the National Institute of Neurological Disorders and Stroke (NINDS) is actively being done to better understand AVMs and to help identify the best treatment options for specific patients.